docs(README): update link for NACS Part 4 article

Author: ankemp

README.md

@@ -25,7 +25,7 @@ This repo is paired with a LinkedIn article series. The five-part series will be
 1. [NACS Part 1: The Hidden Architectural Tax — Why Build-Time Composition Wins](https://www.linkedin.com/pulse/nacs-part-1-hidden-architectural-tax-why-build-time-composition-kemp-gzuhc/)
 2. [NACS Part 2: One Config File. One Client. Zero Leaked Features](https://www.linkedin.com/pulse/nacs-part-2-one-config-file-client-zero-leaked-features-andrew-kemp-qmfec)
 3. [NACS Part 3: A Platform Nobody Uses Is Just a Tax](https://www.linkedin.com/pulse/nacs-part-3-platform-nobody-uses-just-tax-andrew-kemp-w4sjc/)
-4. NACS Part 4: The Shell That Doesn't Know What It Contains
+4. [NACS Part 4: The Shell That Doesn't Know What It Contains](https://www.linkedin.com/pulse/nacs-part-4-shell-doesnt-know-what-contains-andrew-kemp-g7g3c/)
 5. NACS Part 5: You Aren't Building a Tool. You're Building a Platform
 
 ## How It Works